2-(Mercaptomethyl)-6-phenyl-3(2H)-pyridazinone O,O-diethyl phosphorodithioate 51356-15-1 BRN 0826747 Phosphorodithioic acid, O,O-diethyl ester, S-ester with 2-(mercaptomethyl)-6-phenyl-3(2H)-pyridazinone